Alert from our friends at American Epilepsy Society – the FDA approved new Warnings and Precautions for the Prescribing Information (PI) regarding cardiac arrhythmias. In vitro testing showed that Lamictal exhibits Class IB antiarrhythmic activity at therapeutically relevant concentrations, so it could slow ventricular conduction (widen QRS) and induce proarrhythmia, including sudden death, in patients with structural heart disease or myocardial ischemia. Avoid the use of Lamictal in patients who have cardiac conduction disorders (i.e., second- or third-degree heart block), ventricular arrhythmias, or cardiac disease or abnormality (i.e., myocardial ischemia, heart failure, structural heart disease, Brugada syndrome, or other sodium channelopathies). Concomitant use of other sodium channel blockers may increase the risk of proarrhythmia. Related updates were made in other sections of the PI, including Pharmacodynamics and Patient Counseling, as well at the Medication Guide.